Shelf stable acid food dressings containing fibrous protein complexes

ABSTRACT

Shelf-stable acidic food dressings having a pH of less than 4.1 comprising an acidic food dressing vehicle and fibrous xanthan gum-protein complexes which retain their firm fibrous texture under prolonged storage conditions. Also disclosed are methods for preparing dressings.

This application is a continuation-in-part of to U.S. application Ser.No. 567,096 and U.S. application Ser. No. 567,277 now U.S. Pat. No.4,559,233, both filed Dec. 30, 1983.

The present invention is directed to shelf stable acidified fluid fooddressings which contain texturally firm protein complex fibers such asmeat analog fiber compositions. More particularly, the present inventionis directed to acidified, emulsified oil dressings and oil-freedressings and the like which contain fibrous xanthan-protein complexesand which are shelf stable at room temperature.

Substantial technological effort has been directed to the development ofacidic food dressings which are microbiologically stable, and suchdressings are conventionally prepared which remain wholesome and have ashelf life at room temperature for at least 6 months or more. Suchacidic food dressings may generally comprise sufficient acid content tohave an aqueous phase pH of less than about 4.1, typically from about2.75 to 3.75, in order to provide microbiological stability at roomtemperature, together with a tart or acidic flavor profile. In thisregard, for example, U.S. Pat. No. 3,955,010 to Chozianin, et al., andU.S. Pat. 4,145,451 to Oles describe shelf stable acidic food dressingswhich remain preserved against spoilage for extended time periods.

It would be desirable to provide shelf-stable acidic food dressingswhich contain firm-textured meat pieces such as shrimp or diced chickenas a flavor and texture enhancing component. However, because of theacidic nature of such food dressings, the texture, firmness and fibrousquality of such meat proteins tend to degrade upon prolonged storage.Natural meat pieces also may present difficulties in the preservation ofmicrobiological stability under prolonged storage, and tend to bufferthe acid content of the dressing.

Accordingly, it is an object of the present invention to provideshelf-stable acidic food dressings containing fibrous proteincompositions which retain their firmness and fibrous textural propertiesin the acid environment of the food dressing. It is a further object toprovide methods for the manufacture of protein complex fibers and fooddressings which have desirable flavor and texture characteristics. It isa further object to provide novel meat-simulating protein compositionswhich may be utilized in acidic food dressings. These and other objectsof the invention will become apparent from the following detaileddescription and the accompanying drawings of which:

FIG. 1 is a schematic diagram illustrating an embodiment of a method formanufacturing an acid, shelf stable food dressing composition;

FIG. 2 is a scanning electron micrograph, at a magnification of 100 X,of an embodiment of a fibrous xanthan gum - soy and protein isolatecomplex which has been in storage testing for approximately 12 months asa component of an acidic food dressing composition in accordance withthe present invention;

FIG. 3 is a scanning electron micrograph, at a magnification of 2000 X,of an embodiment of a fibrous xanthan gum, soy protein and whey proteincomplex which has been in storage testing for approximately 12 months asa component of an acidic food dressing composition in accordance withthe present invention; and

FIG. 4 is a scanning electron micrograph, at a magnification of 2000 X,of an embodiment of a fibrous xanthan gum, whey and egg white proteincomplex which has been in storage testing for approximately two monthsas a component of an acidic food dressing in accordance with the presentinvention.

Generally, the present invention is directed to shelf stable acidic fooddressings comprising a blend of an acidic aqueous fluid food dressingvehicle having a pH of less than about 4.1 and a firm-bodied xanthangum-protein fiber complex composition which retains its fibrous form andtexture in the acidic food dressing vehicle. The shelf-stable foodcomposition will generally comprise from about 0.25 to about 50 percentby weight, and preferably from about 1 to about 10 percent by weight ofthe xanthan gum-protein fiber composition, and from about 50 percent toabout 99.75 percent by weight, and preferably from about 90 percent toabout 99 percent by weight of the aqueous fluid food dressing vehicle,based on the total weight of the food dressing.

The food dressing vehicle utilized in accordance with the presentinvention will generally contain from about 20 to about 96 percent byweight of water, and sufficient acidifying agent to provide the aqueouscomponent of the dressing vehicle with a pH of less than 4.1, andpreferably in the range of from about 2.75 to about 3.75. On accordancewith conventional food dressing manufacture, depending on the desiredpH, the amount of water in the dressing vehicle and the effect ofadditional components of the food dressing, the acidifying agent willgenerally be present in an amount of from about .1 to about 3.5 weightpercent based on the total weight of the food dressing vehicle.

Also in accordance with conventional acid dressing manufacture, the fooddressing vehicle may contain up to about 20 weight percent of a bodyingagent such as gums, starch or other hydrocolloids and mixtures thereof,from about 0 to about 5 percent salt, from about 0 to about 30 percentsweetener, and from about 0 to about 15 percent spices and flavors,based on the total weight of the food dressing vehicle. The fooddressing vehicle which may be utilized includes oils or oil-lessdressings, pourable or viscous dressings and emulsified or nonemulsifiedfood dressing products commonly used as an adjunct on salads,vegetables, sandwiches and the like. Included within such classificationare products such as mayonnaise, salad dressing and French dressing, andimitations thereof, as well as low calorie oil-less products, includingcondiments or reduced calorie products, and other emulsified andnonemulsified oil-containing products. A typical acidic, fluid highoil-containing dressing for salads, which may be either pourable orsemisolid, might have the following composition with percentage valuesof acetic acid and phosphoric acid expressed as weight percent of themoisture present in the composition, but other ingredients expressed asweight percent of the total composition:

    ______________________________________                                                     Weight Percent                                                   Ingredient     Range    Specific Example                                      ______________________________________                                        Oil            30-60    50.0                                                  Moisture       20-50    38.65                                                 Egg Yolk       0-8      4.0                                                   Sweetener      0.4      2.0                                                   Salt           0-4      1.5                                                   Starch         0-4      0.0                                                   Gum              0-1.5  0.75                                                  Spices and Flavors                                                                           0-5      2.0                                                   Acetic Acid    0.05-1.8 1.0                                                   Phosphoric Acid                                                                              0.1-1.5  0.1                                                   ______________________________________                                    

A typical acidic, fluid low oil-containing dressing for salad, which maybe either pourable or semisolid, might have the following compositionwith percentage value of acetic acid and phosphoric acid expressed asweight percent of the moisture present in the composition, but otheringredients expressed as weight percent of the total composition:

    ______________________________________                                                     Weight Percent                                                   Ingredient     Range    Specific Example                                      ______________________________________                                        Oil            10-15    10.0                                                  Moisture       35-90    64.5                                                  Sweetener       0-10    8.0                                                   Egg Yolk       0-7      4.0                                                   Salt           0-4      2.0                                                   Starch          0-10    6.0                                                   Gum             0-11    1.5                                                   Spices and Flavors                                                                           0-5      2.8                                                   Acetic Acid    0.05-1.8 1.0                                                   Phosphoric Acid                                                                              0.1-1.5  0.2                                                   ______________________________________                                    

A typical oil-less dressing, for example, for condiments, might have thefollowing composition with percentage values of acetic acid andphosphoric acid expressed as weight percent of the moisture present inthe composition, but other ingredients expressed as weight percent ofthe total composition:

    ______________________________________                                                     Weight Percent                                                   Ingredient     Range     Specific Example                                     ______________________________________                                        Oil            1.5       1.0                                                  Moisture       55-96     65.3                                                 Egg Yolk       0-20      5.0                                                  MSNF           0-15      5.0                                                  Sweetener      0-30      10.0                                                 Salt           0-5       2.0                                                  Gum            0-15      1.5                                                  Starch         0-20      6.0                                                  Spices and Flavors                                                                           0-15      3.0                                                  Acetic Acid    0.05-1.8  1.0                                                  Phosphoric Acid                                                                              0.1-1.5   0.2                                                  ______________________________________                                    

These formulations are presented by way of example only and otherformulations for dressings for salad are well known in the art.Similarly, techniques for the manufacture of dressing products of thetypes described herein are well known and within the skill of the art.

The ingredients that are utilized in food dressing compositions are alsowell known. The oil may be any of the well known edible triglycerideoils derived from oil seeds, for example, corn oil, soybean oil,safflower oil, cottonseed oil, etc., or mixtures thereof. The sweetenerused is typically sucrose. However, other sweeteners such as dextrose,fructose, corn syrup solids and synthetic sweeteners may also beutilized.

Any suitable emulsifying agent may be used in the salad dressingcompositions of the invention. In this connection, egg yolk solids,protein, gum arabic, carob bean gum, guar gum, gum karaya, gumtragacanth, carrageenan, pectin, propylene glycol esters of alginicacid, sodium carboxymethyl-cellulose, polysorbates and mixtures thereofmay be used as emulsifying agents in accordance with conventional fooddressing manufacturing practices. The use of emulsifying agents isoptional and depends upon the particular type of emulsified oil beingprepared. Emulsifying agents, when used, may typically be present atlevels of from about 1 percent to about 10 percent, depending on theparticular emulsifying agent used.

A bodying agent may be used in the food dressing vehicle to providedesired body or viscosity in accordance with conventional practice. Thebodying agent may be a starch paste or may comprise an edible gum suchas xanthan gum, guar gum, propylene glycol ester of alginic acid(hereinafter "PGA") or the like. Starch, if used, may typically bepresent at a level of from about 2 percent to about 10 percent. Theedible gum will typically be present at lower levels to provide desiredbody and texture.

Starch paste is generally used as a bodying agent in the preparation ofsemisolid emulsified oil dressings, such as salad dressing, and may beused in the preparation of pourable emulsified oil dressings, such asFrench dressing. The starch may be utilized at a level of from about 1to about 8 percent by weight in semisolid dressings and at a level offrom 0 percent to about 8 percent in pourable dressings. Any suitablestarch containing material may be used, and in this connection, any foodstarch, whether modified, unmodified or pregelatinized, tapioca flour,potato flour, wheat flour, rye flour, rice flour or mixtures thereof maybe used as a bodying agent in the preparation of food dressing vehicles.Similarly, the bodying agent may comprise edible gums individually or incombination, and the gums will usually provide the desired body andtexture at levels below those normally required when starch paste isused. The gums, when used as a bodying agent, may typically be presentat a level of between about 0.25 percent and 2.5 percent. Various otheringredients, such as spices and other flavoring agents, andpreservatives such as sorbic acid (including salts thereof) may also beincluded in effective amounts.

As previously indicated, the dressing vehicle has an aqueous pH of about4.1 or lower, preferably in the range of from about 2.75 to about 3.75.Any suitable edible acid or mixture of acid may be used to provide therequired level of acidity in the emulsified dressing compositions of theinvention. Suitable edible acids include lactic acid, citric acid,phosphoric acid, hydrochloric acid, and acetic acid and mixturesthereof. Mixtures of acetic acid and phosphoric acid are particularlypreferred acidifying agents. The amount utilized to achieve a desired pHwill depend on a variety of factors known in the art including thebuffering capacity of protein components of the dressing.

As also indicated, xanthan gum-protein fiber complex compositions are animportant component of the food dressings of the present invention. Suchfibrous complexes will generally comprise from about 20 to about 85percent water, and from about 5 to about 75 percent fibrously complexedxanthan gum and protein. The fibrous complexes may further includeadditional components incorporated in the fibrous structure of thecomplex, such as from about 0 to about 40 weight percent of edible oil,and from about 0 to about 50 weight percent of carbohydrate based on thetotal weight of the fiber composition. The fiber compositions mayfurther include a flavoring agent, which may generally be used at alevel of from about 0 to about 5 percent by weight, and may includepieces of natural meat fibers as a flavoring component. The fibers maybe incorporated directly in the food dressing vehicle, or morepreferably will be heat set in a fiber agglomerate form, with or withouta suitable binder, which may be diced prior to introduction into thefood dressing vehicle. The fiber composition will desirably be formedinto fiber agglomerates having a mass of less than about 2 grams, andmore preferably from about 0.02 grams to about 1.5 grams. Fiberagglomerates may be formed by pressing the fibers, with or without abinding agent, to form a knitted fiber mass. The fiber composition maybe dried to have a lower water content, but such dried fibercompositions will absorb water upon combination with the food dressingvehicle.

Such fibers may be prepared by providing an aqueous protein fibergenerating solution comprising a suitable solubilized edible proteinpolymer component or mixtures of protein polymer components having anisoelectric point greater than pH 3. Suitable proteins include vegetableproteins such as legume proteins and cereal proteins and animal proteinssuch as dairy proteins and egg proteins. Suitable vegetable proteinsinclude soy protein, peanut proteing and oilseed protein such ascottonseed protein, faba bean protein and sunflower seed protein.Suitable dairy proteins include casein and whey protein. Suitable eggproteins include egg white protein and defatted egg yolk protein. Whilevegetable protein isolates such as soy protein isolate, cottonseedprotein isolate, peanut protein isolate, faba bean protein isolate,sunflower protein isolate and pea protein isolates are preferred proteincomponents, xanthan-protein complex fibers may be prepared from lessrefined, or unrefined protein sources. For example, finely dividednatural vegetable seed and bean protein sources such as soy meal, groundwhole soybean, soy milk, and cottonseed flour may be utilized as proteinsources in the fiber generating solution. Soy protein isolate, mixturesof soy protein isolate and egg albumin, and mixtures of soy proteinisolates and whey protein are particularly preferred edible proteinpolymer components. By "solubilized protein" is meant a protein that ishydrated by existing either in true solution (single phase) or in astabilized dispersion which upon initial dispersion in water may appearto be a single phase but after a period of time may separate into twophases. The edible protein polymer component(s) will desirably have anisoelectric point(s) greater than about 3, preferably in the range offrom about 4 to about 12. Particularly useful proteins may have anisoelectric point in the range of from about 4 to about 7. In thisregard, typically soy protein isolate may have an isoelectric point ofabout 4.5, egg albumin of about 4.7 and casein of about 4.5. It is notedthat various constituents of the solubilized edible protein componentmay have different isoelectric points.

The protein components are desirably solubilized at a pH of at leastabout 1 pH unit and preferably at least about 2 pH units from theirisoelectric points. By a "protein isolate" is meant a proteinpreparation containing about 90% protein. The fiber generating solutionfurther includes a solubilized xanthan gum hydrocolloid polymercomponent selected from the group consisting of xanthan gum, xanthangum/hydrocolloid adducts and mixtures thereof. By "xanthan gum" is meantthe heteropolysaccharide produced by fermentation of the microorganismof the genus Xanthomonas. A discussion of the physical and chemicalproperties may be found in Industrial Gums, R. L. Whistler, Ed.,Academic Press, N.Y. (1973), p. 473. Xanthan gum forms adducts withother hydrocolloids such as carob gum in which it is believed that theextended linear nature of the xanthan gum in solution is preserved.Desirably, the xanthan gum adducts should comprise at least about 60weight percent of xanthan gum, based on the total weight of the xanthangum and the adduct component.

The fiber generating solution may be provided in any suitable manner, asby preparing and subsequently combining separate protein components andxanthan gum polymer solutions, and by initially preparing a solutioncomprising both components. The fiber generating solution should bestcontain a solubilized protein component and xanthan component in aparticular range, and in this regard, the total solubilized protein andxanthan components may be in the range of from about 0.1 weight percentto about 4 weight percent, based on the total weight of the aqueousfiber generating solution.

The aqueous fiber forming solution may further include other components,including other dissolved or suspended protein components, flavoringagents, carbohydrates, emulsified or suspended oils or fats,preservatives and hydrocolloids. Such additional materials should not beincluded in amounts which prevent fiber formation, or which producefibers which are unsuited for the intended purpose. When utilizingunrefined or partially refined protein sources such as bean or seedmeals, the fiber generating solution will include substantial quantitiesof nonprotein components such as carbohydrates and fats or oils derivedfrom the source of the protein. For example, soy meal may typicallycontain about 40 percent protein, about 20 percent oil, and about 35percent carbohydrate, while defatted cottonseed meal (moisture about 10percent) may typically contain 53 percent protein and 27 percentcarbohydrate, based on the total weight of the meal. Carbohydrates, suchas corn starch, and edible fats and oils, particularly in emulsifiedform, may also be incorporated in the fiber forming solution. Fats andoils may desirably be incorporated in the fiber forming solution atlevels of up to 70 weight percent, based on the total weight of theprotein. Desirably, the carbohydrate to protein weight ratio in thefiber forming solution should best not exceed about 7 to about 1 andmore preferably about 4 to about 1.

For example, soy-xanthan complex fibers of moderate textural propertiesmay be prepared from blends of soy meal naturally containing about 35weight percent protein and about 32 weight percent carbohydrate, withground corn starch in up to 2:1 weight ratio of corn starch to soyflour, but increasing the weight ratio to 3:1 or more produces weakfibers. Because fiber forming capacity of different proteins withxanthan gum differs, the ability to tolerate additives may depend on theprotein component and will generally be at least in part a function ofthe protein(s) utilized in the fiber forming solution.

To form fibers, the pH of the fiber generating solution may be adjustedto a pH at which the components form a complex, which is preferablywithin about 2 pH units of an optimum isoelectric pH for the desiredcomplex, to form a fibrous protein-xanthan complex under conditions ofmixing of the fiber forming solution. In this manner, hybrid proteincomplexes may be formed which have a fibrous-meat like texture. Thefiber formation is spontaneous and does not require the use of spinningequipment. Once the fibers are formed, they are relatively stable to arange of salt and pH conditions. Moreover, the fibrous network syneresesto produce fibers having a lower water content than the fiber formingsolution. The fibers under some conditions may be less dense than theaqueous phase and thus float to the surface for harvesting by skimmingthe surface of the reaction vessel or draining away the aqueous phasefrom below such as in a standard cheese vat. The separation of thefibrous hybrid protein complexes from the liquid phase, which maycontain low molecular weight solutes, effectively removes salts from theprotein-complex while at the same time concentrating the proteincomponent.

The adjustment of pH to form fibers from the xanthan gum - proteinmixture may be carried out in a variety of ways. In this regard, theprotein fiber generating solution may be provided at a pH significantlyabove the isoelectric point of the protein complex fibers, andsubsequently reduced in pH toward its isoelectric point. This pHreduction may be carried out for example by removal of a cationiccounterion (e.g., Na+) of the solubilized xanthan gum and/or proteincomponent as by electrophoresis, or by addition of an edible or foodgrade acid, such as hydrochloric acid, phosphoric acid, acetic acid,citric acid, ascorbic acid, carbonic acid or mixtures thereof.Adjustment of pH may also be carried out by other appropriate techniquessuch as by combining an aqueous solution of the protein component at apredetermined pH at which the protein component is solubilized, with anaqueous solution of the xanthan gum component at a predetermined pH atwhich it is solubilized, such that upon combination, the resultingsolution has a predetermined pH at or near the isoelectric point of adesired protein-xanthan gum fibrous complex. The fibrous complexreaction is completed or maximized when the gum-protein mixture isadjusted to a pH at which the electrophoretic mobility of a desiredgum-protein mixture is substantially zero.

The isoelectric points of the specified protein component and thexanthan gum component may have widely different values, for example, theisoelectric point of a soy protein isolate component may typically beabout pH 4.4., while xanthan gum, because it may have substantially onlypendant anionic carboxylic acid ionic species, has an effective negativecharge even at pH 1. Soy protein isolate-xanthan fibrous complexes willhave intermediate isoelectric points, depending upon the relativeproportions of each in the complex. Desirably, the isoelectric point ofthe protein-xanthan gum complex fibers may approximate the pH of theacid food dressing vehicle and will be in the range of from about pH 3to about 4.1.

The shape and size of the gum-protein fibers may be controlled by thedegree of shear or mixing applied to the fiber forming solution duringpH adjustment, and the rate of pH adjustment. The texture of thegum-protein complex may be controlled by varying the weight ratio of thexanthan gum component to the protein component. As indicated, a desiredxanthan gum to protein weight ratio is within the range between 1:4 and1:10. Percentages given herein are weight percentages, and ratios areweight to weight ratios unless otherwise indicated.

The ionic strength of the fiber-forming solution is a very importantparameter in respect to fiber formation, and in this regard, should beless than about 1 M, and preferably should be in the range of from about0 M to about 0.1 M. In many cases it is difficult to calculate the ionicstrength. The difficulty is alleviated by measuring the specificconductance of the solution. The specific conductance of the reactionmixture may desirably be less than about 0.09 mho cm⁻¹, and preferablyshould be in the range of from about 0.0004 to about 0.002 mho percentimeter. The formed fibers may desirably be washed to remove salts,drained, pressed to remove moisture and heat-set in agglomerated orunagglomerated form such as by boiling or otherwise heating the fibers.The fibers may also be blended with a suitable binding agent such as eggalbumin, and heat set in agglomerated form. Of course, flavoring agetsmay also be incorporated in or blended with the fiber composition.

Having generally described protein fiber manufacture, various aspects ofthe invention will be further described with respect to methodsillustrated in FIG. 1. As shown in FIG. 1, an aqueous protein solutionsuch as a soy protein isolate solution 10 may be prepared from acommercially available soy protein isolate at a level of 3.6 weightpercent, and having a solution pH of about 7.0. Similarly, a xanthan gumsolution 12 may be prepared by dissolving Keltrol xanthan gum, a productof Kelco, Inc. at a level of about 0.6 weight percent. The solutions 10,12 may be combined in desired ratio to provide a fiber generatingsolution 14 having about 2 weight percent total solids and a pH of about6.6.

The pH, ionic strength, gum/protein ratio, percent total solids,temperature, mode of mixing and stirring and rate of acidification areimportant factors for synthesizing fibers of xanthan gum-proteincomplexes, utilizing the fiber generating solution 14. Such pHadjustment may be carried out by addition of a suitable acid such ashydrochloric acid to neutralize in part the carboxylates of the proteinand the gum so that the repulsion between the two polymers can beminimized. Then, electrostatic interaction and other bondings such ashydrogen bonding, hydrophobic bonding and van der Waals' forces betweenthe two polymers can take place to provide fibers 16 and a whey phase 18which may be separated by appropriate means.

The temperature of the protein-gum interaction as carried out is alsoimportant. A high temperature is not generally desired for forming thefibers of the xanthan gum-soy protein complex. Softer and finer fibersmay be obtained when the gum and the protein are heated to or above 70°C. before the two polymers were mixed and acidified.

The rate of acidification of the fiber-forming solution together withthe rate of application of shear is a further important factor affectingfiber formation. In this regard, a relatively slow rate of acidificationof the mixture of xanthan gum and soy protein may be used for generatingfibers. Addition of all the required amounts of acid into thegum-protein mixture at once may produce gummy or slimy fibers. However,it has been found that substantially all of the acidifying agent may beadded to the fiber forming solution, and permitted to diffuse underrelatively quiescent conditions (e.g., for about a minute), followed bystirring to produce fibers. The whey 18 separated from the fibercomposition 16 may contain inorganic salts resulting from the pHadjustment step, and may contain some unreacted xanthan gum or othercomponents. The inorganic salts and other undesired components (if any)may be removed, at least in part, to provide a deionized whey, which maybe utilized in a recyclic manner in the provision of the protein and gumsolutions 10, 12. The fiber composition may be boiled to provide aproduct 20 which has a distinct fibrous character. The boiled fibrousproduct 20 may be blended and agglomerated with a suitable binding agentsuch as egg whites, heat-set at a pasteurization temperature and dicedto provide a diced fiber agglomerate 22.

An acidic food dressing vehicle 24 may be prepared in accordance withconventional practice, and may, if desired be pasteurized to provide apasteurized dressing 26. The dressing vehicle 26 and the diced fiberagglomerate 22 may be blended to provide a shelf-stable, firm fibercontaining food dressing 28.

Although the method of FIG. 1 has been particularly described withrespect to soy protein-xanthan gum complex fibers, other water solubleproteins may also be utilized to form meat-like fibers. In this regard,for example, casein such as provided by skim milk powder or as sodiumcaseinate, other vegetable proteins such as peanut protein isolate, andegg albumin such as provided by egg whites, may be utilized as thesolubilized protein component to form fibrous hybrid protein complexeswhich are relatively bland but differ in color and texture.Casein-xanthan fibers are white and tough while peanut protein isolateand soy protein-xanthan gum fibers are somewhat softer. The ratio ofdifferent protein components may be varied to provide fibrous productshaving a corresponding variety of characteristics.

Upon formation, the complexed gum-protein fibers may be readilyseparated from the remaining aqueous phase component in any suitablemanner, as by filtration or centrifugation. For example, such fibers maybe harvested by separating them from the aqueous phase, washing themwith water, and pressing them in a cheese-press to provide meat-likefibers that contain generally from about 65 to about 80 weight percentmoisture, and typically about 65 percent by weight moisture. Theincorporation of additional components such as edible oil emulsion inthe fiber forming solution may increase the solids content andcorrespondingly reduce the total water content. The press dried fibersmay be flavored by immersing them in a suitable favoring agent such aslobster, crab, chicken, shrimp, pork or beef extracts or artificialflavors to obtain desired, chewable meat-like products having meatsimulating flavor and texture.

Heat treatment of the protein gum-complex fibers, particularly at ornear their isoelectric point, may significantly increase (e.g., double)the firmness of the fibers and further results in stabilization of thefibers to retain their firmness.

The moisture content of the drain-dried fibers will generally be in therange of 75 to about 90 percent. However, the fibers, as precipitated,or after heat stabilization may be substantially reduced in moisturecontent to provide a low moisture fiber product which retains its fiberintegrity.

The moisture content of pressed fibers will generally be in the range offrom 60 to about 75 percent, although the presence of fats, oils and/orcarbohydrates may affect overall moisture content. The time and pressureof pressing can be varied depending upon the firmness and water-holdingactivity of the fibers and upon the moisture content desired in thefinished products. As previously discussed, drain-dried fibers maynormally hold a substantial amount of water (e.g., about 80 percent byweight) which may function to dissolve the flavoring agents and whichmay also function to hydrate a binding agent such as dried egg whites.Nevertheless, some of the flavoring agents and/or the binder may besqueezed out of the fibers upon pressing. In order to minimize the lossof the flavoring agent and the binder, the fibers may desirably bedehydrated, to a certain extent, by centrifugation before flavoring. Theamount of water expelled from the fibers may be regulated by varying thespeed and time of centrifugation.

The flavored and pressed fiber agglomerates may be heat-set by raisingthe temperature of the blended fiber and binder mixture to, for example,the boiling temperature of water in the blend. Such heating may beaccomplished by means of conventional hot air, thermal radiation,conduction or microwave ovens.

The heat set fiber agglomerates may be cut into suitable sized piecesfor the food dressing composition, or the fiber agglomerates may beoriginally heat set in the form of pieces of desired size.

The food dressing vehicle and the xanthan-protein fiber complexcomposition component may be combined in any suitable manner to formcompositions in accordance with the present invention. Both the dressingvehicle and the fiber composition may be desirably heated, if desired,to a pasteurization temperature of at least about 75° C. at a pH of lessthan 4.1, and combined under aseptic conditions. However, the heat-setfibers may be combined with various dressing vehicles, withoutpasteurization of the vehicle or the blend, to provide a shelf-stabledressing product.

Having generally described the invention, various additional aspectswill be presented by the following examples.

EXAMPLE 1 Preparation of Xanthan-Protein Fibers

Twenty-five grams of soy protein isolate prepared in a conventionalmanner without processing aids is suspended in 2800 milliliters ofdistilled water in a blender. Twenty-five grams of dried egg whites arethoroughly dispersed in the soy protein suspension. To the aqueoussoy/egg white blend is added 8.33 grams of food grade xanthan gum, whichis thoroughly mixed therewith. The xanthan-soy-egg white slurry formedthereby is acidified with 35 milliliters of one molar hydrochloric acid,with stirring, to generate xanthan-protein fibers. The fibers arepermitted to synerese for 20 minutes, after which they are collected,placed on a screen and washed with 8 liters of cold tap water. Thewashed, drain dried fibers are subsequently boiled in 2 liters of waterfor 5 minutes. The boiled, washed fibers are collected, boiled with 4liters of cold tap water and drain dried to produce 322 grams of draindried boiled fibers. Water is squeezed from the fibers, and a portion ofthe fibers are placed into a conventional acidic, fluid 1000 Islandsalad dressing having a pH of 3.5. The fibers are found to retain a verygood, chewy texture despite the low pH, and to derive a desirable flavorfrom the flavor of the salad dressing. Importantly, the fibers areobserved to remain very firm even after storage in the salad dressingovernight in a refrigerator.

EXAMPLE 2 Preparation of Xanthan Protein Fibers

Fifteen batches of xanthan-soy protein isolate protein blends areprepared in the manner of Example 1 and combined. Approximately 2.8liter aliquots of the combined slurry are individually acidified with 35milliliters of one molar hydrochloric acid to produce xanthan-proteinfibers. The resulting fibers are collected from each of the 15preparations and are combined, washed and boiled for 5 minutes to heatset the fibers. The boiled fibers were immediately washed with cold tapwater and dried to provide 4.5 Kg of boiled, washed and drain driedfibers of xanthan-soy protein-albumin (1:3:3) complex fibers. A portionof the boiled, washed and drain dried fibers (designated herein as"fiber product no. 1") was retained for use in acidic salad dressingvehicles.

A portion of the boiled, washed and drain dried fiber was blended with 5percent, based on the fiber weight, of dried egg white powder. Theblended, unflavored fibers were pressed in a tofu frame cheese press andthe pressed slab was heated to heat-set the fiber matrix to provide anunflavor fiber agglomerate (designated herein as "fiber product no. 2").

A second portion of the boiled, washed and drain dried fibers wasblended with 5 percent of dried egg white powder and 5 percent of acommercially available chicken flavor (Haarmann & Reimer's ChickenFlavor R-6598). The flavored fibers were pressed in a tofu frame cheesepress and the resulting pressed slab was heated to heat-set the fibermatrix to provide a chicken flavored fiber agglomerate (designatedherein as "fiber product no. 3").

Xanthan-protein fibers are prepared in a manner substantially the sameas that described in Example 1, except that in each run, the proteinsource utilized consisted of 30 grams of dried egg whites and 20 gramsof whey protein concentrate. The xanthan utilized for each batch was8.33 grams. The fibers from 10 batch preparations were collected, washedon a screen with cold water and heat set by being introduced intoboiling water for 10 minutes. The boiled fibers were washed with coldwater, and dewatered by pressing. 750 grams of the dewatered fibers wereblended with 37.5 grams of spray dried egg whites and 22.5 grams ofsoybean oil. The blend was pressed for 2 hours at 40 psi, removed andcut into 1/2 inch strips which were heat set in a microwave oven. Aportion of the pressed, heat-set fibers was saved for mechanical testing("shrimp control sample").

The protein fiber strips were dried, and mixed with canthaxanthin powderand microwaved to fix the color. The chunks were washed with both hotand cold water to remove a portion of the color, to provide a fiberagglomerate piece which simulates the texture and appearance of shrimp.

(EXAMPLE 3 Preparation of Acidic Food Dressing Vehicle

Ten pounds of an oil free Italian dressing vehicle are prepared havingthe following formulation:

    ______________________________________                                        Oil Free Italian Dressing                                                     Ingredients       Weight Percent                                              ______________________________________                                        Water             84.717                                                      120 grams Vinegar 5.450                                                       Salt              3.767                                                       Sugar             3.600                                                       Gum Mix           0.48                                                        Phosphoric Acid   0.143                                                       Seasonings and flavorings                                                                       0.1793                                                      ______________________________________                                    

After emulsification, the vehicle had a viscosity of 3900 centipoise at80° F.

The gums and sugar are blended, dissolved in water. The acidiccomponents are added to the gum/sugar mixture followed by the salt andremaining components. The product had an immediate viscosity of 920centipoise and an acid content of 0.88 weight percent total acidity,calculated as acetic acid.

Ten pounds of a creamy buttermilk dressing vehicle were also preparedhaving the following formulation:

    ______________________________________                                        Creamy Buttermilk Dressing                                                    Ingredients          Weight Percent                                           ______________________________________                                        Soybean Oil          52.600                                                   Water                9.721                                                    Sugar                2.000                                                    Lactic Acid 88%      0.850                                                    Cultured dairy products                                                                            29.500                                                   Salt                 1.700                                                    Gums, stabilizers and preservatives                                                                1.729                                                    Seasonings and flavorings                                                                          1.900                                                    ______________________________________                                    

The gums and stabilizers are slurried with a portion of the soybean oil.Cultured dairy products, sugar and flavoring agents are added and themixture is heated to 175° F. to pasteurize the mixture. The pasteurizedmixture is combined with cold water and oil slurry and the remainingingredients are combined and homogenized to provide a dressing vehiclehaving a viscosity of 4600 centipoise and an acid content of 0.71, aspreviously described.

Ten pounds of a creamy shrimp emulsified oil dressing vehicle wereprepared in a manner similar to the preparation of the Buttermilkdressing vehicle, having the following composition:

    ______________________________________                                        Ingredients          Weight Percent                                           ______________________________________                                        Soybean Oil          48.0                                                     Water                33.94                                                    Cultured dairy product                                                                             9.0                                                      Sugar                4.55                                                     Salt                 1.50                                                     Lactic Acid          0.70                                                     Gums, stabilizers and preservatives                                                                0.837                                                    Seasonings and flavorings                                                                          1.47                                                     ______________________________________                                    

EXAMPLE 4 Preparation of Stable Xanthan

Protein Fiber Complex Food Dressings

A food dressing (designated herein as "Food Dressing No. 1") is preparedby blending the oil free Italian dressing vehicle of Example 3 with 4percent by weight, based on the total weight of the dressing mixture ofsmall chicken flavored cubes (Xanthan-protein fiber product no. 3 ofExample 2) cut to have a side dimension of approximately 1/8 inch.

Another food dressing (designated herein as "Dressing No. 2") isprepared by combining the oil free Italian dressing vehicle of Example 3with 1 percent of unflavored fibers (Xanthan-Protein fiber product no. 2of Example 2), based on the total weight of the dressing.

A third food dressing (designated herein as "Dressing No. 3") wasprepared by combining 92 percent by weight buttermilk dressing vehicleof Example No. 3 with 8 percent by weight of chicken flavored chunks(xanthan-protein fiber product No. 3 of Example 2) based on the totalweight of the dressing. The chunks were cut to be variable in sizeranging from ═ inch to 1/4 inch in side length.

A fourth dressing (designated herein as "Dressing No. 4") was preparedby combining 94 weight percent buttermilk dressing vehicle of ExampleNo. 3 with two weight percent of chicken flavor, and four weight percentof unflavored chunks (fiber product no. 2 of Example 2) based on theweight of the dressing vehicle.

Another dressing (designated herein as Dressing No. 5") is also preparedby combining a conventional taco flavor dressing vehicle with 4 percentby weight based on the total weight of the taco flavored dressing, ofunflavored xanthan-protein cubes having a side dimension of 1/4 inch(Xanthan-protein fiber product no. 2 of Example 2).

A sixth dressing (designated herein as Dressing No. 6") is prepared bymixing 3 weight percent unpressed fibers (fiber product No. 1 of Example2) with a 97 weight percent conventional cocktail sauce vehicle, basedon the total weight of the resulting dressing. The fiber product, whichgives the appearance of crabmeat in the cocktail sauce. The fibers takeup the flavor of the cocktail sauce.

Similarly, another dressing (designated herein s Dressing No. 7") isalso prepared by mixing 4 weight percent of relatively large unflavoredchunks or cubes (fiber product no. 2 of Example 2) having a sidedimension of approximately 3/8 inch with 96 percent of a conventionalsweet and sour sauce vehicle, based on the total weight of the dressing.

The food dressings containing the xanthan-protein fibers were evaluatedas attractive and were found to have good texture, and consistencytogether with well balanced flavor profiles. It was noted that whileunflavored fibers seem to acquire the flavor of the dressing vehicle,distinct flavors were retained by those containing a flavoring agent.

The dressings were stored in a refrigerator for approximately 12 months(363 days) at 38° F. and were periodically examined for biologicalstability and stability of the protein fiber component. After 12 monthsof storage, the pH of each of the dressings is measured as presented inthe following table:

    ______________________________________                                        Sample                pH                                                      ______________________________________                                        Dressing No. 1                                                                Oil-free italian w/4% small                                                                         3.05                                                    chicken flavored chunks                                                       Dressing No. 2                                                                Oil-free italian w/1% unflavored                                                                    2.65                                                    fibers                                                                        Dressing No. 3                                                                Buttermilk dressing with 8%                                                                         3.58                                                    Chicken flavored chunks                                                       Dressing No. 4                                                                2% Chicken flavor in dressings                                                                      3.93                                                    & 4% unflavored chunks                                                        Dressing No. 5                                                                RC Taco dressing with 4%                                                                            3.52                                                    unflavored chunks                                                             Dressing No. 6                                                                Cocktail sauce with 3%                                                                              3.62                                                    unflavored fibers                                                             Dressing No. 7                                                                Sweet and Sour sauces w/4%                                                                          3.22                                                    large chunks                                                                  ______________________________________                                    

Dressings 1, 2 and 7 are tasted after the 12 month storage testingperiod and were determined to have good texture or very good texture.Dressings 1 and 5 contained suficient fiber material for texturalevaluation, and accordingly, the fiber chunks were removed from therespective dressings and washed to remove adhering dressing material.The samples were allowed to air dry for about 1-11/2 hours and weresubjected to mechanical textural evaluation, as will be descibedhereinafter.

An additional food dressing (designated herein as "Dressing No. 8") isprepared by mixing the shrimp dresing vehicle of Example 3 with theshrimp analog chunks described in Example 2, to provide a shrimp analogdressing having a composition of 93.5% of the dressing vehicle, 4.0% ofthe shrimp analog protein complex, 0.25% chopped onion and 0.40%dehydrated celery. The dressing product is tasted at the time offormulation and is found to have textural properties similar to acontrol sample made from freeze dried shrimp. The dressing product isstored for approximately 2 months at a temperature of 38° F. After twomonth storage, the product is tasted and is found to have a goodtexture. The pH after 2 months storage is 3.35. Portions of the fiberchunks are removed from the dressing and washed as previously described,for physical textural evaluation.

As described, the xanthan-protein complex fibers in the form ofcompressed diced cubes and free fibers were incorporated into a varietyof salad dressing mixtures and underwent shelf stability testing. Theability of the fibers to maintain a firm bodied structural integrity inthe low pH environment of the salad dressings was determined both bysubjective taste tests and by physiocochemical instrumental analysis.

Samples were extruded from a cylindrical extrusion cell having a borediameter of 12.5 mm, a stroke of 75 mm, through a cylindrical extrusionorifice having a length of 6 mm and a diameter of 1.5 mm, using anInstron Universal Testing Machine Model #1122. A cross head speed of 50mm/min was used to extrude the samples. The average maximum forcedeveloped at 45° F. was used as a measure of structural firmness of thesamples. Fiber chunks were extracted from dressings after aging, aspreviously described. Control unaged product was also measured in twoinstances. The following results show that product after aging stillretained good structural integrity.

    ______________________________________                                        Fiber                                                                         Chunks in                                                                              Dressing                 Avg. Maximum                                Dressing No.                                                                           Vehicle   pH      Age    Force                                       ______________________________________                                        1        OF Italian                                                                              3.05    12 mo. 167 ± 2                                                                            kg                                  5        RC Taco   3.52    12 mo. 109 ± 1                                                                            kg                                  8        Shrimp    3.35     2 mo. 88.3 ± 3                                                                           kg                                  Shrimp Control - Example 2                                                                            51.3 ± 4.5                                                                           kg                                          ______________________________________                                    

The xanthan-protein complex fibers were examined by Scanning ElectronMicroscopy (SEM) both before and after aging in low pH salad dressingsystems. FIG. 2 is a SEM micrograph of a portion of the fiber productextruded from dressing no. 1 after the 12 month storage period at amagnification of 100. FIG. 3 is a SEM micrograph of the fiber productextracted from dressing no. 5 after the 12 month storage period at amagnification of 2000. FIG. 4 is a SEM micrograph of the fiber removedfrom dressing no. 8 after the 2 month storage period, at a magnificationof 200. The results displayed in FIGS. 2-4 show that the fibrous natureof the material is retained even after up to 12 months at low pH.

Accordingly, it will be appreciated that in accordance with the presentinvention, shelf-stable acidic food dressings are provided whichcomprise fibrous, meat simulating protein compositions. While thepresent invention has been described with respect to variousembodiments, it will be appreciated that various modifications andadaptations may be made based on the present disclosure, which areregarded to be within the spirit and scope of the present invention.

Various of the features of the invention are set forth in the followingclaims.

What is claimed is:
 1. A shelf-stable acidic food dressing comprising ablend of from about 50 percent by weight to about 99.75 percent byweight of an acidic, aqueous food dressing vehicle having a pH of lessthan about 4.1 and from about 0.25 to about 50 percent by weight of afirm-bodied xanthan gum-protein fiber complex.
 2. A shelf-stable acidicfood dressing in accordance with claim 1 wherein said xanthangum-protein fiber complex is a fibrous heat-set complex of xanthan gumand a protein or protein mixture having an isoelectric point of at leastpH
 3. 3. A shelf-stable acidic food dressing in accordance with claim 2wherein said dressing vehicle has a pH in the range of from about 2.75to about 3.75 and wherein said xanthan gum-protein fiber complexcomprises from about 20 to about 80 percent water and from about 5 toabout 75 percent complexed xanthan gum and protein.
 4. A shelf-stablefood dressing in accordance with claim 1 wherein, said xanthan-proteincomplex is in the form of shrimp or chicken fiber agglomerates having amass of less than about 2 grams.
 5. A shelf-stable food dressing inaccordance with claim 1 wherein said fibrous xanthan-protein complex hasan isoelectric point of less than about 4.1.
 6. A method for preparing ashelf-stable food dressing comprising the steps of preparing axanthan-protein fibrous complex, preparing an aqueous, acidic fooddressing and combining the food dressing and the xanthan-protein fibrouscomplex to provide a shelf-stable aqueous food dressing containing meatsimulating fibers which retain their textures under prolonged storage atacid pH of less than 4.1